The invention is related to a mixing valve layout for a hydraulic system. The mixing valve arrangement comprises a mixing cylinder, a mixing piston and a drive, said drive moving the mixing piston axially with regards to the mixing cylinder, for the passage of different amounts of medium into the mixing cylinder. The invention is also related to an oil cooling system with said mixing valve arrangement as well as a compressor system equipped with said cooling system.
Mixing valve arrangements are required for most diverse technical implementations, when different media or similar media with distinct properties are to be mixed in large volumes. A typical application is the mixing of fluid media, specifically water, oil or other hydraulic fluids, for the provision of a pre-set initial temperature of the medium, for which purpose a medium component with a higher temperature is mixed with a medium component of a lower temperature. The mixing valve arrangement so controls the temperature of the mixed medium to be provided via the flow mixtures of both media components.
From EP 2 484 911 A2 an arrangement is known for the control of the operating temperature at an oil injected pressurized-air compressor, comprising a temperature-controlled mixing valve for the preparation of oil at a desired temperature. The valve has a control element of varying size.
From EP 2 526 297 B1 a compressor system is known, which uses a valve in the lubricant circuit. In a valve housing a mixing compartment is provided, in which hot and/or cooled lubricant are variably entered and mixed. A collar arrangement inside the valve housing is connected to an external actuator, said actuator moving the collar axially between a first and a second position in the housing.
The afore-mentioned solution has the disadvantage that the actuator outside of the valve housing is to be connected to the collar via a thrust rod which must be directed through the housing. Normally, a high pressure is generated in the valve housing, causing sealing issues at the passage point between the valve housing and the axially movable thrust rod. The leakage of lubricant at this point is a permanent unavoidable issue. The actuator must also produce great forces, as not only must it overcome great frictional forces at the sealing points for the axial movement of the collar, but also does it counteract the pressure available in the valve housing.